Cardio Question

Guys serious question has anyone tried fasted cardio? I have looked around for more information about it and benefits but there does not seem to be a whole lot of research supporting either way on this good or bad. I guess I am looking for your opinions is it helpful? Do you feel a difference?

Guys serious question has anyone tried fasted cardio? I have looked around for more information about it and benefits but there does not seem to be a whole lot of research supporting either way on this good or bad. I guess I am looking for your opinions is it helpful? Do you feel a difference?

Try it. If you find bad effects happening then stop. Didn't work for me.

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I have no issue with fasted cardio but usually only do it on the weekends when I run mornings instead of the evenings during the week. I ran fasted 8 miles yesterday at 8:00 pace after doing an hour chest, shoulder & tri workout. As far as effectiveness at burning fat: I only think it makes a difference when you are already on the leaner side and only slight at that.

Guys serious question has anyone tried fasted cardio? I have looked around for more information about it and benefits but there does not seem to be a whole lot of research supporting either way on this good or bad. I guess I am looking for your opinions is it helpful? Do you feel a difference?

It works for some, and there are conflicting studies. For me, I'm not a big fan. I did it to cut for a bb comp and it got me shredded, but I lost a pretty solid amount of muscle. It might have been from overtraining and having carbs too low for an extended period of time, but that experience has steered me away from fasted cardio.

If you are doing it for convinience purposes for low intensity cardio its not a big issue. If your goal is to improve body composition and you are doing higher intensity cardio or HIIT (recommended) then there's a good chance you are cutting yourself short.

Many trainees pigeonhole weight training as an activity exclusively for building muscle, and cardio exclusively for burning fat. On the contrary, weight training can yield very similar results to cardio of similar intensity when 24-hr energy expenditure and macronutrient oxidation is measured [1]. The obvious advantage of weight training is the higher potential for lean mass and strength gains. In the bodybuilding context, cardio should be viewed as merely an adjunctive training mode to further energy expenditure and cross-complement the adaptations specific to weight training. As far as cardio being absolutely necessary for cardiovascular health, well, that depends upon the overall volume and magnitude of your weight training - another topic for another time.

Chaos theory strikes again

On the surface, it seems logical to separate carbs from cardio if you want a maximal degree of fat oxidation to occur during training. But, there’s the underlying mistake - focusing on stored fuel usage during training instead of focusing on optimally partitioning exogenous fuel for maximal lipolytic effect around the clock. Put another way, it’s a better objective to coincide your carb intake with your day’s thermic peaks, where insulin sensitivity & lean tissue reception to carbs is highest. For some reason, this logic is not easily accepted, nor understood. As we know, human physiology doesn’t always cooperate with logic or popular opinion, so let’s scrutinize the science behind the claims.

Civitarese’s team found glucose ingestion during exercise to blunt lipolysis via decreasing the gene expression involved in fat oxidation in untrained men [5]. Wallis’ team saw suppressed fat oxidation in moderately trained men & women when glucose was ingested during exercise [6].

In contrast to the above trials on beginning and intermediate trainees, Coyle’s team repeatedly showed that carb ingestion during moderate-intensity (65-75% VO2 max) does not reduce fat oxidation during the first 120 min of exercise in trained men [7,8]. Interestingly, the intensity margin proximal to where fat oxidation is highest was unaffected by carb ingestion, and remained so for the first 2 hours of exercise.

Horowitz’ team examined the effect of a during-training solution of high-glycemic carbs on moderately trained men undergoing either low intensity exercise (25% VO2 max) or high-moderate intensity (68% VO2 max) [9]. Similar results to Coyle’s work were seen. Subjects completed a 2-hr cycling bout, and ingested the carb solution at 30, 60, and 90 minutes in. In the low-intensity treatment, fat oxidation was not reduced below fasted-state control group’s levels until 80-90 min of exercise. In the 68% group, no difference in fat oxidation was seen whether subjects were fasted or fed throughout the trial.

Further supporting the evidence in favor of fed cardio in trained men, Febbraio’s team investigated the effects of carb ingestion pre & during training in easily one of the best-designed trials on this topic [10]. Subjects exercised for 2 hrs at an intensity level of 63% VO2 max, which is now known as the point of maximal fat oxidation during exercise. Result? Pre & during-training carbs increased performance - and there was no difference in total fat oxidation between the fasted and fed subjects. Despite the elevated insulin levels in the carb-fueled groups, there was no difference in fat availability or fat utilization.

Summing Up the Research Findings

• At low intensities (25-50% VO2 max), carbs during exercise reduce fat oxidation compared to fasted trainees.
• At moderate intensities (63-68% VO2 max) carbs during exercise may reduce fat oxidation in untrained subjects, but do not reduce fat oxidation in trained subjects for at least the first 80-120 minutes of exercise.
• Carbohydrate during exercise spares liver glycogen, which is among the most critical factors for anticatabolism during hypocaloric & other conditions of metabolic stress. This protective hepatic effect is absent in fasted cardio.
• At the established intensity level of peak fat oxidation (~63% VO2 max), carbohydrate increases performance without any suppression of fat oxidation in trained subjects.